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What I/H are you using? Are the spring pads uncut? What length valve is it you need?



We are shooting for around the 1.800" IH range. The spring possibilities really open in that range. We haven't touched the heads with any tooling, other than to see what valve cutter insert might work best on the Serdi (by hand). I haven't looked over the spring pad thickness possibility yet. We will look at that as an option to get the best spring IH. The Hughes valves are 5.014" OAL from what I measured. That is 0.100" longer than stock by advertisement. That should set us up at 1.750" for IH. So a 5.065" OAL might fit the bill, but it might not also hurt to have some more valve above the retainer, so just say 5.100" OAL should be close.

It is the old pluses and minuses game here. Taller valves helps spring selection and stud clearance, but hurts push rod clearance on intake face of head. It also adds weight, albeit a small amount.